The “invisible box challenge,” in which people appear to be walking on air, is the latest Internet trend to go viral. The challenge started to take off when a football player named Dontez Hines and then a cheerleader named Ariel Olivar expertly navigated the trick.

So far, the challenge appears to lack the controversy that’s accompanied other challenges, such as the Blue Whale Challenge. People all over social media have attempted to emulate the trick, although many have not pulled it off anywhere near as flawlessly as Olivar and Hines. Some people just look silly.

Here’s what you need to know:

1. Ariel Olivar’s Video Has Hundreds of Thousands of Likes & Retweets

“Challenge accepted,” Olivar wrote before patting the imaginary box and then appearing to step on it. The video, which you can watch at the top of this article, has been retweeted more than 121,000 times and has more than 240,000 likes. The cheerleader also tweeted a “part two.” That video is above.

Part two shows Olivar appearing to fall when another cheerleader kicks the “box” out from under her. According to The Houston Chronicle, Olivar is a junior at Manvel High School in Texas. On December 4, Olivar revealed on Twitter that she was invited to appear on the Today Show. “guess who’s gonna be on the today show tomorrow morning💋,” she wrote.

2. It’s Important to Keep Your Leg in Exactly the Same Spot to Perform the Challenge

The Houston Chronicle asked Olivar to explain how she performed the trick so well because a lot of people want to emulate it. The trick, she said, is keeping your leg in the same spot. “Honestly, that was the first time I had ever tried it,” she said to the newspaper. “The video was my third time trying it. It’s hard to explain, I just keep the leg in the same exact spot. It is actually kind of challenging keeping it there. The technique, if you want to make it look like [the video], is to bring the other leg higher than the other as if you are actually stepping over a box.”

Ariel told the Houston newspaper that she never thought the trick would go national. “I thought it was just going to be around my school, I didn’t think it would get this far,” Ariel said to the Chronicle. “News reporters have been contacting me, asking to use [the video]. It’s just mind blowing, I didn’t think it would get this far.”

3. A Football Player Also Performed the Trick With Great Ease

According to UK Daily Mail, Ariel Olivar, although her video is getting a lot of attention, is not the only person to dazzle with their ability to perform the challenge. “Some have performed the trick to perfection such as Anderson University football player Dontez Hines,” the site reported. In fact, Hines’ video, which is still on Twitter, dates to August 2017.

The trick dates to at least 2014, reports Daily Mail. “The invisible box trick seems to go back a while, with a few posts on Reddit asking how to pull it off. In a video posted to YouTube, dancer Marcos Grados, from Guadalajara, Mexico, is seen completing the move during a performance. In one of the first instances seen of this trick, back in August 2014, the video has been viewed almost 889,000 times,” the British news site reports.

A Twitter user spotted Hines’ video in late November and sent it viral as well after writing, “how tf you step in mid air.. I’ve literally replayed this video over and over and still am confused.” Hines explained to Men’s Health that he “came up with the idea while waiting around to take pictures with his football team one August morning.” The magazine quoted him as saying, “I realized I had got it down pretty well because of the reactions of my teammates. I had my friend record me… he ended up posting it on his Snapchat. I still cannot believe how much attention it has gotten.”

4. Many People on Social Media Have Attempted the Trick & Some of the Results Are Laughable

It’s hard to succeed at the challenge, judging from some of the valiant, but goofy, attempts to perform it that are flying around on social media. Some people just look like they are hopping, not like they are walking on air. Here are some of the attempts people have shared on Twitter:

5. The Challenge Takes Strength & Flexibility to Pull Off

Men’s Health fitness editor Ebenezer Samuel told the magazine that the challenge “does take a ton of strength and stability to pull off the illusion. Essentially, Samuel said, Hines is doing a one-legged hop forward with a lot of elevation.”

Samuel explained to Men’s Health that “The leg on the step, first of all, is using a lot of hip flexor, glute and core stability.” The magazine quoted him as saying: “All his hip stabilizers on the right side are firing on overtime to hold that hip in position. You’ll notice his body rotates toward the leg on the step as well; there’s a ton of oblique and ab stability maintaining that position…Very explosive hip flexor, abdominal and glute strength is what is driving the leg up and over the box.”